The Ren'Py Visual Novel Engine
Open game and rendering engine packed into a JavaScript framework
A modular Common Lisp game engine
Real Time Strategy game engine supporting early Westwood classics
Flax Engine, multi-platform 3D game engine
Multi-platform 2D and 3D game engine
Python MUD/MUX/MUSH/MU* development system
A .NET ascii/ansi console engine written in C# for MonoGame and XNA
A dead simple 2D game engine for Go
Visual Basic 6 2D online adventure game engine
A simple cross-platform game engine for creating old-school 2D games
API (C#) for simulating certain aspects of a ZX spectrum for porting.
Game framework with AI
Modified source engine (2017) developed by valve and leaked in 2020
Mini game engine for games104
Cross-platform 3D scene editor based on three.js, golang and mongodb
2D Game Engine with Lua Scripting made on top of SFML
Multi-threaded game engine for Android
Modern AS3 Game Engine
Turbulenz is a modular 3D and 2D game framework
C++ OpenSource Game Fabric based on SDL2
2D - 3D game engine
OSGET is the first open source mobile game engine template.
A DirectX based graphics/physics engine